The long-term objective of this proposal is to understand the mechanisms by which Wuchereria bancrofti infection in mothers influences the immunopathology of this helminthiasis in offspring. Previous epidemiologic and immunologic studies of populations in endemic areas indicate that maternal microfilaremia correlates with an increased propensity to develop microfilaremia and diminished antigen-specific T cell reactivity in offspring. We will test hypothesis that this maternally-induced tolerance to filariae is a result of prenatal sensitization to filarial antigens, which in the course of natural infection results in activation of parasite-specific Th2-like cells. Specific aims are: 1. To determine in cross-sectional and prospective epidemiologic studies the influence of maternal microfilarial status on the parasitologic and clinical manifestations of W. bancrofti infection in offspring up to the age of 4 years. 2. To examine the correlation between Ag-specific sensitization of newborns (antigen-driven cord blood B and T cell responses) and maternal infection status. These studies will provide insight into how maternal infection status influences the clinical and immunologic manifestations of human lymphatic filariasis.